"The security of interim president Guaido is a concern", Abrams told a group of reporters.
Though the opposition largely boycotted the 2018 presidential election last May-and they were criticized as fraudulent by some-Maduro won with more than 67 percent of the vote.
Trump tweets: "Maduro willing to negotiate with opposition in Venezuela following us sanctions and the cutting off of oil revenues".
"We will not allow a Vietnam in Latin America".
"If the USA intends to intervene against us they will get a Vietnam worse than they could have imagined".
In an interview with Russia's RIA Novosti agency, Maduro said he was willing to negotiate with the opposition and even offered to bring forward legislative elections - though dismissed the idea of a new presidential poll.
Mr Maduro said the talks could be held with mediation of other countries.
The disputed president Nicolás Maduro is still clinging on to power and has broken diplomatic ties with the USA government.
"Donald Trump has without doubt given an order to kill me and has told the government of Colombia and the Colombian mafia to kill me", Maduro told RIA.
National security adviser John Bolton tweeted that traders should not deal in gold, oil or other commodities "being stolen" from the Venezuelan people, as opponents of Maduro's government anxious that a Russian-operated plane had shipped gold out of Caracas on Wednesday afternoon.
Speaking Tuesday outside the National Assembly, Guaido said he was aware of personal risks. "Our hope is that, in what we believe will be the final period of the regime, it does not use violence to try to prolong its days in power", Abrams said.
US charges Chinese telecom giant Huawei with fraud, stealing trade secrets
It alleged the two executives tried to steal robotic technology from USA carrier T-Mobile to test smartphones' durability. The seriousness of these charges primarily surrounds Huawei's alleged violation of the US sanctions against Iran.
While the USA has recognized president of the National Assembly, Juan Guaido, as "Interim President" of the country, Maduro said that while he believes new parliamentary elections should be held the next presidential election would not be until 2025, as scheduled.
Pompeo said Tuesday the certification will "help Venezuela's legitimate government safeguard those assets for the benefit of the Venezuelan people".
GLOBAL STANDOFF The United States is Venezuela's largest crude importer, ahead of India and China, but the new measures limit transactions between US companies and state oil company PDVSA.
Fuel in Venezuela is practically free: one dollar can buy more than 300 million liters of fuel but only a kilogram (2.2 pounds) of onions.
Maduro has been in charge since 2013 but his re-election in May was branded illegitimate by the European Union, United States and the Organization of American States.
The president said that he would like them to support the dialogue in Venezuela.
Supporters of opposition leader Juan Guaido, who last week swore himself in as the interim president, waved flags and banners.
The 35-year-old National Assembly president, an engineer by training, is attempting to force the 56-year-old Maduro from power so he can set up a transitional government and hold new presidential elections.
In a tweet Wednesday, Trump repeated a travel advisory from the State Department, telling USA citizens not go to Venezuela.
Protester Cesar Gonzalez, 55, said he wants his children and grandchildren to return to the country.